Sift the flour, sugar, baking powder together into a large mixing
bowl. Add the oil, tangerine juice and 1 tsp. of the peel, water,
and egg yolks. Beat the mixture with a wooden spoon until the batter
is smooth. Let rest while:

Beat the eggs whites until they are foamy, then add cream of tartar.
Beat until stiff peaks form. Fold the batter into the egg whites (I
find this keeps the cake evenly-textured, rather than the other way
around.)

Pour into an unbuttered tube pan (I use an angel food cake pan, to
ensure it doesn't stick when unmolding) and bake for 50 minutes.
Knife test for doneness.

Take the cake out of the oven and turn the pan upside-down. If your
pan doesn't have prongs that stick up, place tube of the pan onto a
bottle. Let cake cool for one hour. Loosen the cake by running a
knife around the inside edges, turn it out of the pan, then pour
GLACE ICING on it. Let icing harden for approximately an
hour-and-a-half before serving.

GLACE ICING: Mix liquid into powdered sugar until somewhat runny.
Mixture should be a little thinner than heavy cream. Mix in
tangerine cake and pour in a steady stream over cake. Be sure to
dribble some down the sides.